Lens flaw?

I came across with a strange thing while tesing focus accuracy on the new 24-120/f4 I puchased today. I have never done this test before so maybe this is normal. If you look at the pictures, you will see what looks like a relatively small circle near number 7. It only becomes visible at f11 and smaller. It also happens to my 50/1.8G but in a bit different location in the frame. Do you know what this is? If this is not normal I would rather get it replaced while I can. Test was done on D800.